Four teams of three rebounders
The coach tosses the ball up for the 1st three players to battle for the rebound. The player that catches the ball is the attacker, and the remaining two players then try to stop the attacker from scoring.
The 1st player to make 2 baskets moves to the end of their line. The winner is the 1st team to get all 3 players through.
On a basket or ball that rebounds outside the key area, the ball is returned to the coach.
Good team defence is five players guarding the ball, not five separate one-on-ones. The shell drill is where that starts, so here is how to teach help-side positioning and rotations from the first week of the season.
Rebounding is the least glamorous thing in basketball and one of the most decisive. It is also almost entirely a habit, which means it is entirely coachable.
Good spacing is only the start. The best modern offences teach players to attack the defence's rotations and play in a permanent 4-on-3 - here is how to coach that read.